The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage cards, are widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones.
Semiconductor memory may be provided within a semiconductor package, which protects the semiconductor memory and enables communication between the memory and a host device. Examples of semiconductor packages include system-in-a-package (SiP) or multichip modules (MCM), where a plurality of die are mounted and interconnected on a small footprint substrate.
Semiconductor die are often stacked in a package in an offset stepped configuration, so that the die bond pads for each die in the stack are accessible for wire bonding. It has been found that as the number of die in a stack increase, warping of one or more upper die in the stack has been detected at the distal end of the one or more die (opposite the proximal ends including the die bond pads). In an offset stepped die stack, the distal ends of the die overhang the die below and are unsupported. This has resulted in the distal ends of one or more die at the top of the stack bending up away from the die stack.